I would consider a full flow drinking water system which would eliminate the need for a separate faucet. I think that 3M and Everpure make them.

We have a whole house water system that provides some treatment and a multi-component system that goes under the sink that we'll be moving from our current house, just need the small dispenser thing. (I do see that some of them look like full faucets, but that's overkill for us.)

Echoing Sherri, I picked the 3M Aquapure Full Flow undercounter system. No separate faucet which makes me very happy :) . I haven't installed it yet, but because it's high flow it should not slow down the water flow.

It really depends on what you are trying to filter from the water, and whether another faucet is really an issue. If you are looking to remove everything from the water, I would suggest a reverse osmosis system. If it is only chlorine and the taste of the water you are concerned about, then the above water filters will do the job.

Here is a link that might be useful: Aquasafe Systems

We have a Kohler faucet and soap dispenser in chrome and a Multipure Aquaversa MP750SB Water Filter. We use it primarily for drinking water. The faucet is available in a number of finishes.

Here is a link that might be useful: Water filter